Help me to pass arrays to functions in 'C'

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C

errors

I am writing a program related to Graph Theory, I wrote code for matrix multiplication by using functions, that worked well. when I am using that function into this program I am getting following errors.

I don't understand why this is happening?

Here I am giving you the part of code from my whole program.

float product(int,int,int,int,float a[20][20],float b[20][20],float c[20][20]);
/*first to integers order of matrix a &
 second two integers are order of matrix b
 and float c is result of a*b */

float yn[ar][ar],temp[ar][ac];
product(ar,ac,ac,ac,incidence,yb,temp);/*calling function*/


float product(int ar,int ac,int br,int bc,float a[20][20],float b[20][20],float c[20][20])
{   int i,j,k;
  if(ac==br)
  {
    for(i=0;i<ar;i++)
    {
      for(j=0;j<bc;j++)
      {
        c[i][j]=0;
        for(k=0;k<ac;k++)
        {
          c[i][j]=c[i][j]+(a[i][k]*b[k][j]);
        }
      }
      printf("\n");
    }
  }
  else
  {
    printf("Please Enter proper matrices");
    return -1;
  }
  return 0;
}

When I run this, I am getting these errors.

prog.c: In function ‘main’:
prog.c:40: warning: passing argument 5 of ‘product’ from incompatible pointer type
prog.c:4: note: expected ‘float (*)[20]’ but argument is of type ‘int (*)[(unsigned int)(ac)]’
prog.c:40: warning: passing argument 6 of ‘product’ from incompatible pointer type
prog.c:4: note: expected ‘float (*)[20]’ but argument is of type ‘int (*)[(unsigned int)(ac)]’